On DZone.com today there's an update about recent additions to Paratest, the parallel PHPUnit test runner (created by Brian Scaturro). He talks some about the benefits of running tests in parallel and shares some of the recent contributions to the project from other developers.

I've already written about my experiments with Paratest. Paratest is a PHPUnit wrapper that allows you to run tests written for PHPUnit in parallel, making us of multiple processes running on the same machine. In a world where cycle time is an important metric, trading resources to get the test suite to finish earlier is a net gain; especially when you're stepping on unstable stones and run the suite very often.

He (Giorgio Sironi) has contributed a new test runner to the project - the "WrapperRunner" that limits the number of processes spawned by the parallel testing tool. Another contribution came from Dimitris Baltas involving the addition of a TEST_TOKEN variable that can be used to uniquely identify each process as they're executing.